qemu/scsi/pr-manager-helper.c
<<
>>
Prefs
   1/*
   2 * Persistent reservation manager that talks to qemu-pr-helper
   3 *
   4 * Copyright (c) 2017 Red Hat, Inc.
   5 *
   6 * Author: Paolo Bonzini <pbonzini@redhat.com>
   7 *
   8 * This code is licensed under the LGPL v2.1 or later.
   9 *
  10 */
  11
  12#include "qemu/osdep.h"
  13#include "qapi/error.h"
  14#include "scsi/constants.h"
  15#include "scsi/pr-manager.h"
  16#include "scsi/utils.h"
  17#include "io/channel.h"
  18#include "io/channel-socket.h"
  19#include "pr-helper.h"
  20#include "qapi/qapi-events-block.h"
  21#include "qemu/module.h"
  22
  23#include <scsi/sg.h>
  24#include "qom/object.h"
  25
  26#define PR_MAX_RECONNECT_ATTEMPTS 5
  27
  28#define TYPE_PR_MANAGER_HELPER "pr-manager-helper"
  29
  30OBJECT_DECLARE_SIMPLE_TYPE(PRManagerHelper, PR_MANAGER_HELPER)
  31
  32struct PRManagerHelper {
  33    /* <private> */
  34    PRManager parent;
  35
  36    char *path;
  37
  38    QemuMutex lock;
  39    QIOChannel *ioc;
  40};
  41
  42static void pr_manager_send_status_changed_event(PRManagerHelper *pr_mgr)
  43{
  44    const char *id = object_get_canonical_path_component(OBJECT(pr_mgr));
  45
  46    if (id) {
  47        qapi_event_send_pr_manager_status_changed(id, !!pr_mgr->ioc);
  48    }
  49}
  50
  51/* Called with lock held.  */
  52static int pr_manager_helper_read(PRManagerHelper *pr_mgr,
  53                                  void *buf, int sz, Error **errp)
  54{
  55    ssize_t r = qio_channel_read_all(pr_mgr->ioc, buf, sz, errp);
  56
  57    if (r < 0) {
  58        object_unref(OBJECT(pr_mgr->ioc));
  59        pr_mgr->ioc = NULL;
  60        pr_manager_send_status_changed_event(pr_mgr);
  61        return -EINVAL;
  62    }
  63
  64    return 0;
  65}
  66
  67/* Called with lock held.  */
  68static int pr_manager_helper_write(PRManagerHelper *pr_mgr,
  69                                   int fd,
  70                                   const void *buf, int sz, Error **errp)
  71{
  72    size_t nfds = (fd != -1);
  73    while (sz > 0) {
  74        struct iovec iov;
  75        ssize_t n_written;
  76
  77        iov.iov_base = (void *)buf;
  78        iov.iov_len = sz;
  79        n_written = qio_channel_writev_full(QIO_CHANNEL(pr_mgr->ioc), &iov, 1,
  80                                            nfds ? &fd : NULL, nfds, errp);
  81
  82        if (n_written <= 0) {
  83            assert(n_written != QIO_CHANNEL_ERR_BLOCK);
  84            object_unref(OBJECT(pr_mgr->ioc));
  85            pr_mgr->ioc = NULL;
  86            pr_manager_send_status_changed_event(pr_mgr);
  87            return n_written < 0 ? -EINVAL : 0;
  88        }
  89
  90        nfds = 0;
  91        buf += n_written;
  92        sz -= n_written;
  93    }
  94
  95    return 0;
  96}
  97
  98/* Called with lock held.  */
  99static int pr_manager_helper_initialize(PRManagerHelper *pr_mgr,
 100                                        Error **errp)
 101{
 102    char *path = g_strdup(pr_mgr->path);
 103    SocketAddress saddr = {
 104        .type = SOCKET_ADDRESS_TYPE_UNIX,
 105        .u.q_unix.path = path
 106    };
 107    QIOChannelSocket *sioc = qio_channel_socket_new();
 108    Error *local_err = NULL;
 109
 110    uint32_t flags;
 111    int r;
 112
 113    assert(!pr_mgr->ioc);
 114    qio_channel_set_name(QIO_CHANNEL(sioc), "pr-manager-helper");
 115    qio_channel_socket_connect_sync(sioc,
 116                                    &saddr,
 117                                    &local_err);
 118    g_free(path);
 119    if (local_err) {
 120        object_unref(OBJECT(sioc));
 121        error_propagate(errp, local_err);
 122        return -ENOTCONN;
 123    }
 124
 125    qio_channel_set_delay(QIO_CHANNEL(sioc), false);
 126    pr_mgr->ioc = QIO_CHANNEL(sioc);
 127
 128    /* A simple feature negotiation protocol, even though there is
 129     * no optional feature right now.
 130     */
 131    r = pr_manager_helper_read(pr_mgr, &flags, sizeof(flags), errp);
 132    if (r < 0) {
 133        goto out_close;
 134    }
 135
 136    flags = 0;
 137    r = pr_manager_helper_write(pr_mgr, -1, &flags, sizeof(flags), errp);
 138    if (r < 0) {
 139        goto out_close;
 140    }
 141
 142    pr_manager_send_status_changed_event(pr_mgr);
 143    return 0;
 144
 145out_close:
 146    object_unref(OBJECT(pr_mgr->ioc));
 147    pr_mgr->ioc = NULL;
 148    return r;
 149}
 150
 151static int pr_manager_helper_run(PRManager *p,
 152                                 int fd, struct sg_io_hdr *io_hdr)
 153{
 154    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
 155
 156    uint32_t len;
 157    PRHelperResponse resp;
 158    int ret;
 159    int expected_dir;
 160    int attempts;
 161    uint8_t cdb[PR_HELPER_CDB_SIZE] = { 0 };
 162
 163    if (!io_hdr->cmd_len || io_hdr->cmd_len > PR_HELPER_CDB_SIZE) {
 164        return -EINVAL;
 165    }
 166
 167    memcpy(cdb, io_hdr->cmdp, io_hdr->cmd_len);
 168    assert(cdb[0] == PERSISTENT_RESERVE_OUT || cdb[0] == PERSISTENT_RESERVE_IN);
 169    expected_dir =
 170        (cdb[0] == PERSISTENT_RESERVE_OUT ? SG_DXFER_TO_DEV : SG_DXFER_FROM_DEV);
 171    if (io_hdr->dxfer_direction != expected_dir) {
 172        return -EINVAL;
 173    }
 174
 175    len = scsi_cdb_xfer(cdb);
 176    if (io_hdr->dxfer_len < len || len > PR_HELPER_DATA_SIZE) {
 177        return -EINVAL;
 178    }
 179
 180    qemu_mutex_lock(&pr_mgr->lock);
 181
 182    /* Try to reconnect while sending the CDB.  */
 183    for (attempts = 0; attempts < PR_MAX_RECONNECT_ATTEMPTS; attempts++) {
 184        if (!pr_mgr->ioc) {
 185            ret = pr_manager_helper_initialize(pr_mgr, NULL);
 186            if (ret < 0) {
 187                qemu_mutex_unlock(&pr_mgr->lock);
 188                g_usleep(G_USEC_PER_SEC);
 189                qemu_mutex_lock(&pr_mgr->lock);
 190                continue;
 191            }
 192        }
 193
 194        ret = pr_manager_helper_write(pr_mgr, fd, cdb, ARRAY_SIZE(cdb), NULL);
 195        if (ret >= 0) {
 196            break;
 197        }
 198    }
 199    if (ret < 0) {
 200        goto out;
 201    }
 202
 203    /* After sending the CDB, any communications failure causes the
 204     * command to fail.  The failure is transient, retrying the command
 205     * will invoke pr_manager_helper_initialize again.
 206     */
 207    if (expected_dir == SG_DXFER_TO_DEV) {
 208        io_hdr->resid = io_hdr->dxfer_len - len;
 209        ret = pr_manager_helper_write(pr_mgr, -1, io_hdr->dxferp, len, NULL);
 210        if (ret < 0) {
 211            goto out;
 212        }
 213    }
 214    ret = pr_manager_helper_read(pr_mgr, &resp, sizeof(resp), NULL);
 215    if (ret < 0) {
 216        goto out;
 217    }
 218
 219    resp.result = be32_to_cpu(resp.result);
 220    resp.sz = be32_to_cpu(resp.sz);
 221    if (io_hdr->dxfer_direction == SG_DXFER_FROM_DEV) {
 222        assert(resp.sz <= io_hdr->dxfer_len);
 223        ret = pr_manager_helper_read(pr_mgr, io_hdr->dxferp, resp.sz, NULL);
 224        if (ret < 0) {
 225            goto out;
 226        }
 227        io_hdr->resid = io_hdr->dxfer_len - resp.sz;
 228    } else {
 229        assert(resp.sz == 0);
 230    }
 231
 232    io_hdr->status = resp.result;
 233    if (resp.result == CHECK_CONDITION) {
 234        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
 235        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, PR_HELPER_SENSE_SIZE);
 236        memcpy(io_hdr->sbp, resp.sense, io_hdr->sb_len_wr);
 237    }
 238
 239out:
 240    if (ret < 0) {
 241        int sense_len = scsi_build_sense(io_hdr->sbp,
 242                                         SENSE_CODE(LUN_COMM_FAILURE));
 243        io_hdr->driver_status = SG_ERR_DRIVER_SENSE;
 244        io_hdr->sb_len_wr = MIN(io_hdr->mx_sb_len, sense_len);
 245        io_hdr->status = CHECK_CONDITION;
 246    }
 247    qemu_mutex_unlock(&pr_mgr->lock);
 248    return ret;
 249}
 250
 251static bool pr_manager_helper_is_connected(PRManager *p)
 252{
 253    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(p);
 254    bool result;
 255
 256    qemu_mutex_lock(&pr_mgr->lock);
 257    result = (pr_mgr->ioc != NULL);
 258    qemu_mutex_unlock(&pr_mgr->lock);
 259
 260    return result;
 261}
 262
 263static void pr_manager_helper_complete(UserCreatable *uc, Error **errp)
 264{
 265    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(uc);
 266
 267    qemu_mutex_lock(&pr_mgr->lock);
 268    pr_manager_helper_initialize(pr_mgr, errp);
 269    qemu_mutex_unlock(&pr_mgr->lock);
 270}
 271
 272static char *get_path(Object *obj, Error **errp)
 273{
 274    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 275
 276    return g_strdup(pr_mgr->path);
 277}
 278
 279static void set_path(Object *obj, const char *str, Error **errp)
 280{
 281    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 282
 283    g_free(pr_mgr->path);
 284    pr_mgr->path = g_strdup(str);
 285}
 286
 287static void pr_manager_helper_instance_finalize(Object *obj)
 288{
 289    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 290
 291    object_unref(OBJECT(pr_mgr->ioc));
 292    qemu_mutex_destroy(&pr_mgr->lock);
 293}
 294
 295static void pr_manager_helper_instance_init(Object *obj)
 296{
 297    PRManagerHelper *pr_mgr = PR_MANAGER_HELPER(obj);
 298
 299    qemu_mutex_init(&pr_mgr->lock);
 300}
 301
 302static void pr_manager_helper_class_init(ObjectClass *klass,
 303                                         void *class_data G_GNUC_UNUSED)
 304{
 305    PRManagerClass *prmgr_klass = PR_MANAGER_CLASS(klass);
 306    UserCreatableClass *uc_klass = USER_CREATABLE_CLASS(klass);
 307
 308    object_class_property_add_str(klass, "path", get_path, set_path);
 309    uc_klass->complete = pr_manager_helper_complete;
 310    prmgr_klass->run = pr_manager_helper_run;
 311    prmgr_klass->is_connected = pr_manager_helper_is_connected;
 312}
 313
 314static const TypeInfo pr_manager_helper_info = {
 315    .parent = TYPE_PR_MANAGER,
 316    .name = TYPE_PR_MANAGER_HELPER,
 317    .instance_size = sizeof(PRManagerHelper),
 318    .instance_init = pr_manager_helper_instance_init,
 319    .instance_finalize = pr_manager_helper_instance_finalize,
 320    .class_init = pr_manager_helper_class_init,
 321};
 322
 323static void pr_manager_helper_register_types(void)
 324{
 325    type_register_static(&pr_manager_helper_info);
 326}
 327
 328type_init(pr_manager_helper_register_types);
 329